A variety of vacuum devices are known in the art that are effective to suction both wet and dry materials. These vacuum devices, which are commonly referred to as “wet/dry vacuums,” typically include a relatively large holding tank having an open top and a suction mechanism, generally comprised of an electric motor and impeller, that is supported on the open top of the holding tank, A hose or other flexible conduit is usually provided having a first end that is generally connected to an inlet fitting on the tank and a second end that is adapted to be positioned by a user.
Materials entering the tank are generally prevented from entering the suction mechanism by one or more of the following: a float valve or mechanism that rises as the level of liquid rises in the tank, thereby shutting off the motor or blocking air from entering the impeller; a filter, for instance of pleated material in the shape of a cylinder, or cloth in the shape of a disk that surrounds a cage or filter assembly, where the float is housed; and a filter bag inside the tank configured so that material suctioned through the hose stays inside the bag when it enters the tank. The bag has an inlet, such as an aperture that engages a first end of the inlet fitting, and a second end of the inlet fitting engages the first end of the hose. When the suction mechanism is operated, the wet and dry materials are drawn through the first end of the hose to the second end of the hose and are deposited within the bag disposed in the holding tank. While a filter around the cage or filter assembly may adequately protect the motor and impeller from dust and debris, and prevent most particulate material from exhausting the vacuum cleaner with the exhausted air, bags are often preferable, instead of or in addition to those filters, Bags contain the debris, so that emptying the tank of debris creates less dust or other mess when a bag is used, Certain high efficiency filters can be fairly expensive, so bags are also desirable as a way to limit the dust and debris engaged by the filter, thereby extending its useful life.
Known bags may be made from a paper material. Such bags are inexpensive and act as an effective filter to trap dirt and other solid debris within the bag. However, when water or other liquids enter the bag, the bag material weakens and may rupture when lifted, such as when removing it from the holding tank. Water may come in contact with a bag because the debris is damp, or a user may begin vacuuming liquids in a hurry, such as when a pipe has burst in a home, without checking to see if there is a bag in the tank. Liquids may have debris mixed into them, and it may be desirable to filter that debris before emptying the tank of liquid into a sump pump or other receptacle that could become clogged by that debris. Bags made of other materials, such as woven or cloth bags, are stronger than paper bags when wet, but such cloth bags are expensive and therefore are not usually suitable for disposable applications. Some cloth bags may also not have desirable filtering characteristics, either when wet or dry. In addition, cloth and other bags have a tendency to “inflate” when damp. That is, air passes less easily through a wet bag than when the bag is dry, resulting in relatively high pressure within the bag compared to the low pressure inside the tank, hut outside the bag. Due to this building pressure, a wet bag will inflate, increasing its volume, and this increase in volume may upwardly displace fluid that is disposed within the tank but outside of the bag. When the rising fluid reaches the float valve, the float valve is triggered and the power to the vacuum cleaner is cut off, despite the fact that there is relatively little fluid in the tank. In addition, cloth bags (and paper bags) may be damaged as debris entering the bag at relatively high velocities impacts a portion of the bag. Accordingly, there exists a need for a bag that is inexpensive, has good filtering characteristics, and is strong when wet and dry, so that it can be used for both wet and dry materials.